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Topic Review (Newest First)

07-02-2012 12:31 PM

Tempest

Re: Centerboard position - keel/centerboard Tartan 37 upwind

Tweegs, Yes, I agree that off the wind in heavier air, the board helps slippage and gives a more neutral helm, since she'll fight to head to wind.

07-02-2012 12:01 PM

Tweegs

Re: Centerboard position - keel/centerboard Tartan 37 upwind

Quote:

Originally Posted by Tempest

Neither of those tactics work on my boat. from 0 to 10 knots or so, I can sail to windward nicely without any board down, above 10 knots, I'll begin to lower the board in increments to help reduces weather helm and leeway, and allow me to point higher...I've been playing with just how much..but, halfway feels right between 10 and 15..above 15 I'd probably lower it completely.

Off the wind, the board starts coming up in increments until when downwind there's no board down.

Thatís been my experience as well.

Also, on a reach in heavier air, we tend to add a little more centerboard to help keep us from slipping sideways, and trim the sails for balance.

Lowering the centerboard in a moderate chop helps stabilize the boat. It stands to reason that if the boat is better stabilized, airflow over the sails will be improved.

I donít think there are any hard and fast rules for centerboard use, just rules of thumb. Your boat will tell you what she needs, you just have to listen to her. But kind of like my wife, knowing exactly what she wants takes some practice and experience.

07-02-2012 10:30 AM

Tempest

Re: Centerboard position - keel/centerboard Tartan 37 upwind

Neither of those tactics work on my boat. from 0 to 10 knots or so, I can sail to windward nicely without any board down, above 10 knots, I'll begin to lower the board in increments to help reduces weather helm and leeway, and allow me to point higher...I've been playing with just how much..but, halfway feels right between 10 and 15..above 15 I'd probably lower it completely.

Off the wind, the board starts coming up in increments until when downwind there's no board down.

07-02-2012 10:11 AM

CalypsoP35

Re: Centerboard position - keel/centerboard Tartan 37 upwind

I just google'd centerboard position and the articles stated the farther forward the boat is the more the boat is forced to head up. So the conclusion was if you are in heavy wind which is creating weather helm, you want less board). If the boat is falling off wind (lee helm) you want more CB.

I'm referring to only upwind sailing here. Off wind the board comes up. I have been able to balance my boat withe CB so that I don't have touch the wheel when I get her balanced.

07-02-2012 09:55 AM

CalypsoP35

Re: Centerboard position - keel/centerboard Tartan 37 upwind

I know this sounds counter intuitive, but I could have sworn that I read an article that stated you need less centerboard in high winds and more in low winds. The reason being that in high winds the boat's greater speed creates more lift. In low wind conditions, you need all the CB you can get because you have less boat speed therefore less lift.

07-02-2012 09:11 AM

Tweegs

Re: Centerboard position - keel/centerboard Tartan 37 upwind

I think you are referring to moving the center of lateral resistance (CLR) to help balance the helm (usually to tame weather helm).

We havenít found a condition yet that moving the centerboard was the best answer. Adjusting the vang, Cunningham, outhaul and/or reducing sail are our first choices. Since the backstay on my boat is on a turnbuckle and not easily adjustable underway, we might put a couple of turns on it before we leave the slip in heavy air, and have to live with the results. If you have an adjustable backstay, throw that in the mix.

07-02-2012 08:33 AM

cspear

Re: Centerboard position - keel/centerboard Tartan 37 upwind

Another question that comes to mind: As I understand it, moving the centerboard up and down does change the position of the draft (perhaps this is the wrong term, I meant the balance) of the boat, doesn't it? Moving that back and forth depending on the position of the centerboard can affect the boat's ability to point, right? Is this offset by the decreased drag?

07-02-2012 08:23 AM

Tweegs

Re: Centerboard position - keel/centerboard Tartan 37 upwind

On my boat in particular, yes, we can point OK in about 5 knots true with the board up. We can come up a little closer with the board down, or partially down, but we can lose up to half a knot of boat speed. Itís more advantageous for us to leave the board up, fall off the extra 2 or 3 degrees and make it up with speed, especially on the 1 or 2 mile legs that we run.

For us, that crossover point between drag vs. lift was right around 10 knots apparent.

Thereís nothing that says my CB is in the best condition though, probably could use some work. Went down for a look a couple of weeks back and found no damage, everything felt smooth enough, but that means nothing. I wear glasses and underwater, even with a mask in clear water, things are still a bit fuzzy.

Iíd like to get that board out of there when we come out this fall. Give it all the attention it needs.

06-29-2012 12:30 PM

SchockT

Re: Centerboard position - keel/centerboard Tartan 37 upwind

I have no experience racing such a creature, but I am surprised that you would get better performance with your centerboard up when beating. I would think the added lift you get from the board would outweigh the drag. Are you able to point with the rest of the fleet with your board up? Looking at images of the keel design it appears that what is left when the board is up is a far from ideal upwind shape.

06-25-2012 09:17 AM

cspear

Re: Centerboard position - keel/centerboard Tartan 37 upwind

Thank you all for the advice.

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